Short answer: use a List if one already exists that closely matches what you want to display in your table view, otherwise use a Results.

If the data represented by a List that's already stored in your Realm corresponds to what you want to display in your table view, you should certainly use that to back it. Lists have an interesting property in that they are implicitly ordered, which can sometimes be helpful, like in the tutorial you linked to above, where a user can reorder tasks.

Results contain the results of a query in Realm. Running this query typically has a higher runtime overhead than accessing a List, by how much depends on the complexity of the query and the number of items in the Realm.

That being said, mutating a List has performance implications too since it's writing to the file in an atomic fashion. So if this is something that will be changing frequently, a Results is likely a better fit.

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